The long term goal of this research project is to increase our understanding of the development of the ability to perceive the spatial layout of the environment and the three-dimensional structure of objects. A new source of information for spatial layout relative motion has been described and we have recently found evidence that adults are sensitive to this cue. The first goal of this program is to investigate the development of sensitivity to relative motion information for spatial layout. Preferential reaching to the apparently closer of two surfaces will be used to assess sensitivity to this depth cue in 5- and 7-month- old infants. The second goal is to explore sensitivity to kinetic information in younger infants. Studies of sensitivity to accretion and deletion of texture and relative motion information for depth will use duration of fixation to investigate whether young infants can use kinetic cues to segment a scene into figure and ground regions. A transfer-across-cue method will be used in this series of experiments. The third objective of this research program is to investigate the onset of the ability of infants to perceive the invariant shape of an object that is undergoing kinetic occlusion. The ability of the infant to use relative motion and accretion and deletion of texture to perceive occlusion of an object and the transformation of an object that is changing shape will be investigated. The fourth objective of this proposal is to investigate the ability of the infant to perceive the properties of an object that is almost entirely occluded, one that is viewed as it moves behind a narrow slit. For veridical perception to take place with these displays, the visual system must register the direction and speed of visible motion. In addition, the visual system must integrate into a single spatial representation information that is only available over time. The fifth goal of this program of study is to compare the attention of young infants to invariant retinal shape with their attention to invariant real shape in parallel constancy studies. The aim of this study is to assess 'constancy' using habituation displays in which a variety of real shapes and only a single retinal shape are presented to the infant. This method should make it possible to explore the development of responses to both distal object and retinal image properties.